Treatment breakthrough for infertile mares

Professor Anders Miki Bojesen and Embryologist Morten Rønn Petersen.
Professor Anders Miki Bojesen and Embryologist Morten Rønn Petersen. © Henrik Petit

Two Danish researchers say they have discovered a major cause of infertility in mares and have tested a treatment regime with positive results.

University of Copenhagen Professor Anders Miki Bojesen and embryologist Morten Rønn Petersen have developed a product to help such horses become pregnant.

It has been successfully tested in the field by veterinarians from the world’s largest horse hospital in Kentucky, and the results were so encouraging that the university assisted in setting up a company to help commercialize the product.

The pair say that the most common cause of a mare’s reduced fertility is a chronic infection in the mucosal membrane of the uterus caused by the bacteria Streptococcus equi subspecies zooepidemicus.

“We noticed that many horses that test negative for streptococci have a dormant infection without showing clinical symptoms,” says Bojesen, from the Department of Veterinary Disease Biology at the University of Copenhagen.

“Despite the lack of symptoms, however, it still seems to reduce the fertility of the mares.”

Ten per cent of mares have difficulties conceiving.

Bojesen joined with Petersen, who works at the Fertility Department at Copenhagen University Hospital, to find a solution to the problem.

From their research, the two managed to activate the dormant bacteria with a product that they call Bactivate.

“Once you wake the bacteria you can diagnose the infection and treat the horses with regular antibiotics,” says Bojesen.

“Streptococci are usually not resistant to antibiotics, but during dormancy the metabolism is so low that antibiotics are rendered useless.

“Bactivate is made up of signalling components that rouse the bacteria and lead them to quickly start dividing and multiplying like normal and treatable streptococci.”

Bactivate was tested at Hagyard Equine Medical Institute in Lexington, Kentucky.

Mares that received Bactivate developed substantial but treatable uterus infections.

Petersen explains: “We tested Bactivate on 64 breeding mares at Hagyard that had demonstrated a substantially reduced ability to conceive.

“Following treatment, 83 per cent of the mares got pregnant within one and a half months and 72 per cent gave birth to a live foal.

“This means that fertility levels basically were normalized in mares that previously had not conceived for several cycles, some for years. When dormant streptococci were activated, the mares were treated and bred in the following cycle.”

Hagyard veterinarian Kristina Lu described the discovery as “an important step forward”.

“At the end of the day it’s an important diagnostic tool because it makes the bacteria grow which means it will definitely play an important role in fertility treatments,” she adds.

Bactivate’s high success rate proved so encouraging that the hospital now has taken on the role of selling the product in the US, while the new company, Bojesen & Petersen Biotech, will make it.

Bactivate is developed for an exclusive group of customers and will initially be sold to treat some of the world’s most valuable thoroughbreds.

Bactivate needs to be approved by the Danish Medicines Agency before it can be sold in Denmark.

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